Hot off the presses! Apr 28 Vaccine

The Apr 28 issue of the Vaccine is now up on Pubget (About Vaccine): if you're at a subscribing institution, just click the link in the latest link at the home page. (Note you'll only be able to get all the PDFs in the issue if your institution subscribes to Pubget.)

Latest Articles Include:

• Editorial Board
  - Vaccine 27(19):CO2 (2009)
  
• Response to "Analysis of adverse events of potential autoimmune aetiology in a large integrated safety database of AS04 adjuvanted vaccines" by Verstraeten et al.
  - Vaccine 27(19):2529 (2009)
  
• Rebuttal Letter to the Letter to the Editor to "Analysis of adverse events of potential autoimmune aetiology in a large integrated safety database of AS04 adjuvanted vaccines" by T. Verstraeten et al.
  - Vaccine 27(19):2530 (2009)
  
• Conclusion on cost-effectiveness of rotavirus vaccination highly dependent on assumptions
  - Vaccine 27(19):2531-2532 (2009)
  
• Comment on "Patel JR, Heldens JGM. Review of companion animal viral diseases and immunoprophylaxis" (Vaccine 2009;27:491–504)
  - Vaccine 27(19):2533 (2009)
  
• Estimating vaccination coverage: Validity of household-retained vaccination cards and parental recall
  - Vaccine 27(19):2534-2539 (2009)
  Public health programs rely on household-survey estimates of vaccination coverage as a basis of programmatic and policy decisions; however, the validity of estimates derived from household-retained vaccination cards and parental recall has not been thoroughly evaluated. Using data from a vaccination coverage survey conducted in the Western Pacific's Northern Mariana Islands, we compared results from household data sources to medical record sources for the same children. We calculated the percentage of children aged 1, 2, and 6 years who received all vaccines recommended by age 12 months, 24 months, and for school entry, respectively. Coverage estimates based on vaccination cards ranged from 14% to 30% in the three age groups compared to 78–91% for the same children based on medical records. When cards were supplemented by parental recall, estimates were 51–53%. Concordance, sensitivity, specificity, positive and negative predictive values, and kappa statistics gene! rally indicated poor agreement between household and medical record sources. Household-retained vaccination cards and parental recall were insufficient sources of information for estimating vaccination coverage in this population. This study emphasizes the importance of identifying reliable sources of vaccination history information and reinforces the need for awareness of the potential limitations of vaccination coverage estimated from surveys that rely on household-retained cards and/or parental recall.
• Safety and immunogenicity of a hexavalent diphtheria–tetanus–acellular pertussis–inactivated poliovirus–Haemophilus influenzae b conjugate–hepatitis B vaccine at 2, 3, 4, and 12–14 months of age
  - Vaccine 27(19):2540-2547 (2009)
  Combination vaccines improve parental and provider satisfaction and schedule compliance by decreasing the number of injections. In a Phase 2, randomized, double-blind, multicenter study, we compared four formulations of a liquid, hexavalent diphtheria–tetanus–acellular pertussis–inactivated poliovirus–Haemophilus influenzae b conjugate–hepatitis B virus (DTaP–IPV–Hib–HBV) vaccine in 708 infants immunized at 2, 3, 4, and 12–14 months of age. The formulations contained identical DTaP and IPV components, differing in the contents of Hib polyribosylribitol phosphate (PRP) conjugate component (tetanus-toxoid [PRP-T, 12 μg] or Neisseria meningitidis outer-membrane-protein-complex [PRP-OMPC, 3 μg or 6 μg]), and in hepatitis B surface antigen (HBsAg, 10 μg or 15 μg). A minimum acceptable postdose 3 antibody response rate was defined by the lower limit of the 95% confidence interval exceeding a prespecified target. Rates of adverse events (AEs) were simil! ar among groups, with a trend for increased solicited injection-site reactions (pain, redness, swelling) with increasing PRP-OMPC and HBsAg concentration. Serious AEs reported by eight subjects were not considered to be vaccine related. All PRP-OMPC formulations met prespecified acceptability criteria for postdose 3 immunogenicity for all antigens: PRP, HBsAg, pertussis, diphtheria, tetanus and polio. Apart from the Hib response, the postdose 3 responses obtained with the PRP-T formulation met the acceptability criterion for each antigen. Postdose 4 responses were acceptable for all antigens in all formulations. All vaccine formulations were well tolerated. The three PRP-OMPC formulations met prespecified immunogenicity criteria, and the one with the lowest PRP-OMPC concentration was selected for further optimization of immunogenicity.
• A vero cell derived combined vaccine against sheep pox and Peste des Petits ruminants for sheep
  - Vaccine 27(19):2548-2553 (2009)
  The combined sheep pox and Peste des Petits ruminants (PPR) vaccine was prepared in lyophilized form containing recommended doses of both vaccine viruses. Safety and immunogenicity of this combined vaccine was evaluated in sheep. Sheep immunized subcutaneously with 1 ml of live attenuated vaccine consisting of 103 TCID50 each of sheep pox virus (SPV) Romanian Fanar (RF) strain and Peste des Petits ruminants virus (PPRV-Sungri/96 strain) were monitored for clinical and serological responses for a period of four weeks post immunization (pi) and two week post challenge (pc). Specific antibodies directed to sheep pox virus could be demonstrated by indirect ELISA and serum neutralization test (SNT). Competitive ELISA and SNT were used for demonstration of antibodies to PPR virus. All the immunized animals resisted challenge with virulent SPV or PPRV on day 30 pi, while control animals developed characteristic signs of disease. Specific virus could be detected in the unvacci! nated control animals after challenge but not from any of the immunized sheep. Combined vaccine was found to be safe and potent as evident from sero conversion as well as challenge studies in sheep. This indicates that component vaccines did not interfere each other and can be used in target population for economic vaccination strategies.
• Qualitative differences in the early immune response to live and killed Leishmania major: Implications for vaccination strategies against Leishmaniasis
  - Vaccine 27(19):2554-2562 (2009)
  Recovery from natural or deliberate infection with Leishmania major leads to the development of lifelong immunity against rechallenge infections. In contrast, vaccination with killed parasites or defined leishmanial antigens generally induces only short-term protection. The reasons for this difference are currently not known but may be related to differences in the quality of the early immune responses to live and killed parasites. Here, we report that live and killed L. major parasites elicit comparable early inflammatory response as evidenced by influx and/or proliferation of cells in the draining lymph nodes (dLNs). In contrast, the early cytokine responses were qualitatively different. Cells from mice inoculated with killed parasites produced significantly more antigen-specific IL-4 and less IFN-γ than those from mice injected with live parasites. Inclusion of CpG ODN into killed parasite preparations changed the early response to killed parasites from IL-4 to a p! redominantly IFN-γ response, resulting in better protection following secondary high dose virulent L. major challenge. Interestingly, CpG-mediated enhancement of killed parasites-induced protection was short-lived and waned after 12 weeks. Taken together, these results suggest that the nature of primary immunity induced by killed and live parasites are qualitatively different and that these differences may account for the differential protection seen in mice following vaccination with live and killed parasites. They further suggest that modulating the early response with an appropriate adjuvant could enhance efficacy of killed parasite vaccines.
• Vaccination coverage against measles in German-born and foreign-born children and identification of unvaccinated subgroups in Germany
  - Vaccine 27(19):2563-2569 (2009)
  Data from the representative German Health Interview and Examination Survey for Children and Adolescents were used to identify unvaccinated subgroups that should be targeted by vaccination programmes in order to interrupt measles transmission. Measles vaccination coverage was low among children below the age of 3, having ≥3 siblings and in foreign-born migrants. Multivariate analyses show that vaccination coverage was strongly related to the place of birth in migrants: foreign-born children have a three-fold odds of being unvaccinated. Odds were also higher in children living in former West Germany, having ≥3 siblings, and it was especially high in children with parents reporting reservations against vaccinations.
• CpG-ODN combined with Neospora caninum lysate, but not with excreted-secreted antigen, enhances protection against infection in mice
  - Vaccine 27(19):2570-2579 (2009)
  CpG oligodeoxynucleotides (ODN) have shown to be potent immunoadjuvants for several pathogens, but there is limited information concerning their use in immunization protocols against neosporosis. This study aimed to evaluate the potential of CpG-ODN combined with Neospora lysate antigen (NLA) or excreted-secreted antigen (NcESA) to induce protective immune response against Neospora caninum infection in mice. C57BL/6 mice were vaccinated subcutaneously three times at 2-week intervals with NLA, NLA + CpG, NcESA, NcESA + CpG, CpG (adjuvant control) or PBS (infection control). Serological assays showed an increased specific IgG2a response in animals immunized with either antigen plus adjuvant and elevated levels of the IgG1 isotype in those vaccinated with antigens alone. Splenocyte proliferative responses upon antigen stimulation were higher in groups immunized with NLA or NcESA combined with CpG, showing increased IL-12 levels. Also, mice vaccinated with NcESA or NcESA +! CpG demonstrated higher IFN-γ levels and IFN-γ/IL-10 ratio. After lethal challenge, mice immunized with NLA + CpG or NLA had lower morbidity score and body weight changes in comparison to other groups, and animals did not succumb during acute infection. In contrast, NcESA + CpG or NcESA groups exhibited the highest morbidity scores, body weight impairment and mortality rates, associated with greatest brain parasite burden and inflammation. In conclusion, CpG-ODN was able to induce a Th1-type humoral immune response with predominant IgG2a levels for either NLA or NcESA, but resulting in an effective Th1-driven cellular immune response and total protection only when combined with NLA. Vaccination with NcESA alone or combined with CpG resulted in a strong cellular immune response associated with high levels of IFN-γ and inflammation, rendering mice more susceptible to parasite challenge.
• Comparative studies of local antibody and cellular immune responses to influenza infection and vaccination with live attenuated reassortant influenza vaccine (LAIV) utilizing a mouse nasal-associated lymphoid tissue (NALT) separation method
  - Vaccine 27(19):2580-2587 (2009)
  The first and most significant barrier against influenza infection is the mucosal-associated lymphoid tissue of the upper airways and rodent nasopharyngeal-associated lymphoid tissue (NALT) is considered equivalent to the lymphoid tissue of human Valdryer's ring. This study is the first attempt to analyze and compare local and systemic cellular and antibody immune responses in NALT and spleen in a mouse model of experimental influenza infection and intranasal vaccination with LAIV (live attenuated reassortant influenza vaccine). It was shown that the vaccine strain completely inherited the ability to induce high-grade local antibody responses (secretory IgA + IgG + IgM), local cellular lymphoproliferative activity, CD4+, CD8+ and CD19+ lymphocyte and cytokine production responses from the virulent parental strain but it had less capacity to stimulate production of serum IgG, accumulation of CD8+ cells and IFN-γ production in the spleen. Primary non-complicated influen! za infection and primary vaccination were accompanied by a short-term (24 h) increase in the levels of lymphocyte apoptosis in both NALT and spleen. However, experimental data indicated that vaccination with LAIV and uncomplicated forms of influenza infection did not influence immune system apoptosis following a secondary immune response.
• Suitability of PER.C6® cells to generate epidemic and pandemic influenza vaccine strains by reverse genetics
  - Vaccine 27(19):2588-2593 (2009)
  Reverse genetics, the generation of influenza viruses from cDNA, presents a rapid method for creating vaccine strains. The technique necessitates the use of cultured cells. Due to technical and regulatory requirements, the choice of cell lines for production of human influenza vaccines is limited. PER.C6® cells, among the most extensively characterized and documented cells, support growth of all influenza viruses tested to date, and can be grown to high densities in large bioreactors in the absence of serum or micro carriers. Here, the suitability of these cells for the generation of influenza viruses by reverse genetics was investigated. A range of viruses reflective of vaccine strains was rescued exclusively using PER.C6 cells by various transfection methods, including an animal component-free procedure. Furthermore, a whole inactivated vaccine carrying the HA and NA segments of A/HK/156/97 (H5N1) that was both rescued from and propagated on PER.C6 cells, conferred ! protection in a mouse model. Thus PER.C6 cells provide an attractive platform for generation of influenza vaccine strains via reverse genetics.
• T-cell vaccines that elicit effective immune responses against HCV in chimpanzees may create greater immune pressure for viral mutation
  - Vaccine 27(19):2594-2602 (2009)
  A prime/boost vaccine strategy that transfects antigen-presenting cells using ligand-modified immunoliposomes to efficiently deliver plasmid DNA, followed by boosting with non-replicating recombinant adenovirus was used in chimpanzees to generate HCV-specific memory T-cells. Three chimpanzees (two vaccines, one control) were immunized with immunoliposomes complexed with DNA expressing NS3-NS5B or complexed with empty vector. Animals were boosted with adenovirus expressing NS3-NS5B, or non-recombinant adenovirus (control). Using liposome delivery we were able to obtain specific HCV responses following DNA priming in the chimpanzees. This data and mouse immunization studies confirm this as a more efficient delivery system than direct intramuscular inoculations with naked DNA. Subsequent to the adenovirus boost significant increases in peripheral HCV-specific T-cell responses and intrahepatic IFN-γ and CD3var epsilon mRNA were also observed in the two vaccinated animals.! Following challenge (100 CID50) both vaccinated animals showed immediate and significant control of viral replication (peak titers 3.7 × 104 and 9 × 103 IU/mL at weeks 1 and 2), which coincided with increases in HCV-specific T-cell responses. Viral kinetics in the control animal were comparable to historical controls with exponential increases in titer during the first several weeks. One vaccinated animal developed a low-level persistent infection (2 × 103 IU/mL) which correlated with a decrease in HCV-specific T-cell responses. Circulating virus isolated from both vaccinated animals showed not, vert, similar2-fold greater nonsynonymous mutation rates compared to controls and the nonsynonymous/synonymous mutation rate ratio was indicative of positive selection. These data suggest that although T-cell vaccines can induce immune responses capable of controlling HCV, they also induce high levels of immune pressure for the potential selection of escape mutants.
• Enhancing DNA vaccination by sequential injection of lymph nodes with plasmid vectors and peptides
  - Vaccine 27(19):2603-2615 (2009)
  DNA vaccines or peptides are capable of inducing specific immunity; however, their translation to the clinic has generally been problematic, primarily due to the reduced magnitude of immune response and poor pharmacokinetics. Herein, we demonstrate that a novel immunization strategy, encompassing sequential exposure of the lymph node milieu to plasmid and peptide in a heterologous prime-boost fashion, results in considerable MHC class I-restricted immunity in mice. Plasmid-primed antigen expression was essential for the generation of a population of central memory T cells, expressing CD62L and low in PD-1, with substantial capability to expand and differentiate to peripheral memory and effector cells, following subsequent exposure to peptide. These vaccine-induced T cells dominated the T cell repertoire, were able to produce large amounts of chemokines and pro-inflammatory cytokines, and recognized tumor cells effectively. In addition to outlining a feasible and effect! ive method to transform plasmid DNA vaccination into a potentially viable immunotherapeutic approach for cancer, this study sheds light on the mechanism of heterologous prime-boost and the considerable heterogeneity of MHC class I-restricted T cell responses.
• Localization of the sites and characterization of the mechanisms by which anti-light chain antibodies neutralize the actions of the botulinum holotoxin
  - Vaccine 27(19):2616-2624 (2009)
  The recombinant, catalytically active light chain of botulinum toxin type A was evaluated as a potential vaccine candidate. Previous studies have shown that the light chain can elicit protective immunity in vivo. [Kiyatkin N, Maksymowych AB, Simpson LL. Induction of immune response by oral administration of recombinant botulinum toxin. Infect Immun 1997;65(11):4586–91], but the underlying basis for this observation was not determined. In the present study, antibodies directed against the light chain were shown to act at three different sites in the body to produce neutralization. Firstly, these antibodies acted to block toxin absorption into the body. This was demonstrated in vitro, in studies on binding and transport of toxin across epithelial monolayers, and in vivo, in studies on inhalation poisoning. Secondly, anti-light chain antibodies acted to promote clearance of toxin from the general circulation. This was demonstrated in vivo in studies on toxin levels in b! lood and in parallel studies on toxin accumulation in liver and spleen. Finally, anti-light chain antibodies acted to protect cholinergic nerves from botulinum toxin action. This was demonstrated in two types of in vitro assays: rate of paralysis of murine phrenic nerve-hemidiaphragm preparations and extent of binding to Neuro-2a cells. When taken together, these data show that anti-light chain antibodies can evoke three layers of protection against botulinum toxin.
• Attitudes towards HPV immunization of Italian mothers of adolescent girls and potential role of health professionals in the immunization program
  - Vaccine 27(19):2625-2629 (2009)
  We assessed the knowledge of Italian mothers of adolescent girls about HPV and HPV vaccination, their willingness to immunize their daughters, and their perception of the role of different medical specialists in the HPV immunization strategy by a telephone interview. Fifty-four percent of the 807 interviewed mothers reported to have ever heard about HPV, and 84% of them were willing to immunize their daughters. Pediatricians most frequently provided information on HPV vaccine (31%), and were perceived as the preferred immunization providers (77%). Acceptance of HPV immunization was high and was not associated with knowledge of HPV.